Refactor OEMCrypto Unit Tests

Merge from widevine repo of http://go/wvgerrit/21681

This CL refactors some oemcrypto unit tests in preparation for adding
Provisioning 3.0 tests.

- The signature GenerateNonce has changed.  Instead of the caller
  passing in a pointer for the nonce, we store the nonce in a member
  variable of Session.

- GenerateDerivedKeys is being replaced by InstallTestSessionKeys.
  This sets up and calls the appropriate derive keys method.  This
  function is in the test class, instead of the session class so that
  multiple sessions in a class can share the same wrapped rsa key.
  This will be modified for provisioning 3.0 in a future CL.

- Rename tests that require a keybox.  Some tests are specific for
  using a keybox to request a DRM cert. These tests are renamed so we
  can filter them out on devices that use an OEM Cert.  Corresponding
  tests for devices using provisioning 3.0 will be in a future CL.

- Some member variables and methods in the class Session were not
  used.  They are removed.

- Added openssl smart pointer.

- Comments.  I added comments.

- clang format.

Change-Id: Ib579a322858e0ef92652a42167241b35cf85a041

libwvdrmengine/cdm/core/test/generic_crypto_unittest.cpp

@@ -33,6 +33,7 @@ class WvGenericOperationsTest : public testing::Test {
   virtual void SetUp() {
     ::testing::Test::SetUp();
 
+    // TODO(fredgc or gmorgan): This should be updated for provisioning 3.0
     // Load test keybox. This keybox will be used by any CryptoSession
     // created by the CDM under test.
     ASSERT_EQ(OEMCrypto_SUCCESS, OEMCrypto_LoadTestKeybox());
@@ -72,7 +73,8 @@ class WvGenericOperationsTest : public testing::Test {
   void OecSessionSetup(uint32_t oec_session_id) {
     buffer_size_ = 160;
     oec_util_session_.SetSessionId(oec_session_id);
-    oec_util_session_.GenerateTestSessionKeys();
+    // TODO(fredgc or gmorgan): This should be updated for provisioning 3.0
+    oec_util_session_.GenerateDerivedKeysFromKeybox();
     MakeFourKeys();
   }
 
@@ -202,7 +204,8 @@ TEST_F(WvGenericOperationsTest, NormalSessionOpenClose) {
 TEST_F(WvGenericOperationsTest, GenerateSessionKeys) {
   wvoec::Session s;
   ASSERT_NO_FATAL_FAILURE(s.open());
-  ASSERT_NO_FATAL_FAILURE(s.GenerateTestSessionKeys());
+  // TODO(fredgc or gmorgan): This should be updated for provisioning 3.0
+  ASSERT_NO_FATAL_FAILURE(s.GenerateDerivedKeysFromKeybox());
   ASSERT_NO_FATAL_FAILURE(s.close());
 }